Impact of Enrichment on the Behavior of Sows Housed in Groups

Drs. Ventura and Zhitnitskiy, faculty members in the College of Food, Agricultural, and Natural Resources and the College of Veterinary Medicine at the University of Minnesota recently published a new article regarding the influence of point-source enrichment on the behavior of gestating sows housed in groups. The article is available in open-access on the Frontiers in Animal Science website.

Key Points

  • Most common observed behaviors were sows being inactive (73%), followed by sham-chewing (16%). Enrichment use made up only 1% of observations.
  • Number of observed interactions with enrichment decreased sharply on the second day.
  • Low-parity sows, moderately-lame sows, and sham-chewing sows interacted more with the enrichment.
  • No increase in adverse effects (agonistic behaviors, sham-chewing) was observed.


This study was a cross-over design in which 40 focal sows were observed for nine days. Day 1 served as a baseline to record behaviors without enrichment being present. Then, half of the sows had access to enrichment toys (Luna, EasyFix) for four days. At that time, the enrichment toys were cleaned and moved to the other pens so that the other half of the sows could interact with them.

Sows were video-recorded for the entire duration of the study and behaviors were captured for each sow every 15 minutes. Additionally, continuous observations were done for each sow for one hour each day to better capture enrichment use.


Overall, focal sows spent ~73% of observations inactive, 16% sham-chewing followed by 3% exploring, 2% feeding, 2% walking, and 1% interacting with the enrichment when it was available. Sows were very rarely observed performing agonistic behaviors.

Fifteen percent of the sows were never observed interacting with the enrichment. Over half (55%) were observed using the enrichment at least two days, whereas 8% of focal sows interacted with enrichment every day of the study. On average, sows spent less than a minute interacting with enrichment (ranging from 0 to 18.7 min per h). However, enrichment toys did not introduce new behavioral problems (no increase in fighting or sham-chewing), but the sows’ interest seemed to decline among most of the sows after the first day.

Interestingly, low-parity sows spent significantly more time interacting with enrichment because of the number of interactions recorded.

Lameness affected sows’ enrichment use so that moderately lame sows appeared to more consistently retain enrichment interaction behaviors whereas sound sows showed a decline in enrichment use after day 1. Similarly, sows observed sham chewing at baseline had a more consistent number of enrichment use bouts over the study, compared to sows who were not observed to sham chew at baseline.

Read the entire article on the journal website.


Environmental enrichment is an important strategy to improve the welfare of farm animals. However, relatively little is known about enrichment for gestating sows, especially those raised on farms with slatted floors and for which provision of straw may be difficult. The objective of this study was therefore to investigate the short-term (4 d) impact of a point-source enrichment object on the behavior of gestating sows housed in group pens. Four pens of gestating sows on a university research farm were randomly allocated to receive either enrichment or no enrichment (control) in a 2 by 2 crossover design. Time budgets were established by video recording focal sows’ behaviors (n = 10 focals per pen) every 15 min between 0800 and 1500 every day. Enrichment use was further characterized by continuous behavior sampling for a 1 h interval between 0830 and 0930 each day. The impact of parity, lameness and presence of stereotypical behavior such as sham chewing on enrichment use was evaluated. Over the course of the study, focal sows spent approximately 73% of observations inactive [either lying down (70%), standing (2%), or sitting (1%)]. Within the remaining observations, sows were most commonly observed sham-chewing (16%), followed by 3% exploring, 2% feeding, 2% walking and 1% interacting with the enrichment when it was available. Low-parity sows, moderately-lame sows, and sows observed sham chewing at baseline displayed more consistent enrichment use over the course of the study (p = 0.02, p < 0.01, p = 0.04, respectively). While no adverse behavioral effects (increased agonism or sham chewing) due to provision or removal of the enrichment object were observed and while 85% of sows were observed to interact with enrichment at least once, interest declined sharply after the first day. We conclude that further research is needed to identify effective and sustainable enrichment strategies for gestating sows.

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